A greenhouse effect due to increase of a carbon dioxide (CO2) concentration is recently pointed out as a cause of a global warming phenomenon, and there is an urgent need for an international countermeasure for protecting an environment on a global basis. A major source of CO2 generation is an industrial activity and momentum is rising to inhibit its emission.
As acid gas separation technology for inhibiting concentration rise of an acid gas such as CO2, a method (absorption method) where the acid gas is absorbed by using a chemical absorbent and recovered is studied. For example, in a facility such as a thermal power plant in which a fossil fuel (coal, petroleum, natural gas, etc.) is used, by bringing an exhaust gas generated at a time of combustion of the fossil fuel into contact with the chemical absorbent, removal and recovery of CO2 in a combustion exhaust gas is performed.
As the chemical absorbent used in the absorption method, it is tried to use alkanolamines. In particular, an amino alcohol aqueous solution which contains a heterocyclic amine compound exhibits an excellent CO2 absorbability.
Demand for a separation and recovery processing of an acid gas such as CO2 tends to increase more and more in recent years, and it is tried to recover a chemical absorbent having been used in a recovery processing of CO2 and to use the chemical absorbent again. However, if the absorbent after being used in the recovery processing of CO2 is used again as it is, corrosion in a contact region is apt to be caused in a plant facility, for example, and there is a possibility that a life duration of the entire facility is reduced. Thus, technology to separate and recover an amino alcohol from an absorbent having been used in a recovery processing of CO2 is demanded.
On the other hand, in a case where an amino alcohol is to be isolated from an amino alcohol aqueous solution containing a heterocyclic amine compound, as the heterocyclic amine compound being apt to evaporate and a vacuum state being hard to be obtained, separation and purification of the amino alcohol and the heterocyclic amine compound is difficult by a purification method such as distillation. Thus, it is difficult to isolate an amino alcohol at a high purity from an amino alcohol aqueous solution containing a heterocyclic amine compound.
As an isolation method of an amino alcohol, there is suggested a method for isolating the amino alcohol or an acid addition salt of the amino alcohol from an amino alcohol aqueous solution. However, an effective means is not yet found for a method for isolating an amino alcohol from an amino alcohol aqueous solution containing a heterocyclic amine compound.